C. Elegans Gene MO3F4.3 is a D2-Like Dopamine Receptor

In C. elegnns there are over 1000 putative G protein-coupled receptor (GPCR) genes, of which approximately 18 are predicted to code for rhodopsin-like GPCRs. Heterotrimeric GTP-binding proteins mediate the response to a wide variety of neurotransmitters and hormones, all of which bind to GPCRs. I have chosen to work on M03F4.3, which is a candidate rhodopsin-like GPCR. Although M03F4.3 is believed to code for a rhodopsin-like GPCR, its functions are not yet clear. To investigate its functions, a region upstream of M03F4.3 putatively containing the complete promoter has been stitched to GFP-encoding DNA and injected into C. elegans hermaphrodites to create transgenic animals. Thus, the expression patterns can be observed with GFP fluorescence. Expression was observed in anterior deirid and cephalic sensilla, vulva, intestine, rectum gland cells, and one posterior cell. The anterior deirid sensilla and the cephalic sensilla comprise two ADE neurons and two CEP neurons, respectively, which are known to respond to dopamine. In addition, a BLASTp search has revealed that C. eleguns genes K09G 1.4 (dop-2), F15A8.5 (dop-I), C02D4.2 (ser-2), K02F2.6 (ser-3), Y22D7AR.13 (ser-4), and C09B7.1 (ser-7) share high similarities, based on amino acid sequence, with M03F4.3. The expression pattern of K09G1.4 is similar to M03F4.3, which makes M03F4.3 a good candidate for expression of dopamine receptor. Furthermore, the regulatory elements that govern the expression of M03F4.3 in were deduced by constructing a series of deletions in the promoter region to GFP and then injecting into C. eleguns hermaphrodites. In addition, experiments with M03F4.3 knockout and dop-I, dop-2, ser-2, ser-3, or ser-7 RNAi constructs have been conducted to determine any changes in mating behavior, locomotion and morphology of both hermaphrodites and males. No changes, however, have been detected. Moreover, phylogenetic tree has been assembled to determine which of two subfamilies, D 1 -like and D2-like dopamine receptors, that M03F4.3 belongs to. The gene clustered with D2-like dopamine receptor encoding genes in different organisms. These findings suggest that M03F4.3 is a likely candidate to code for a D2-like dopamine receptor.